Corals are marine animals that often live in tropical seas. Many types of corals have unicellular algae living in their tissues. The algae provide up to 98 percent of the corals' food. The corals provide protection and inorganic nutrients for the algae.

Algae leave the coral when the water is too warm. What kind of factor is temperature on this relationship?

The deer tick feeds on the blood of the red squirrel, deer, and deer mouse. Which of these best describes the role of the deer tick in the forest food web?

When gypsy moth caterpillars hatch, which of these populations benefits first?

Black skimmers are water birds that live along coastal beaches, bays, estuaries, and marshes. They fly just above the surface of the water using their lower jaw to catch small fish, shrimp, and other small crustaceans.

These birds nest in simple, unlined depressions in the sand. Scientists have observed a decline in the number of nests. Some causes of this decline include a lack of suitable nesting sites, beach erosion, and human disturbances.

When people approach their nests, the birds become aggressive and chase away intruders. Other animals, like crows, will take advantage of the unprotected nests and feed on the eggs.

Which of these best describes the effects of human disturbance on the black skimmer's eggs?

Black skimmers are water birds that live along coastal beaches, bays, estuaries, and marshes. They fly just above the surface of the water using their lower jaw to catch small fish, shrimp, and other small crustaceans.

These birds nest in simple, unlined depressions in the sand. Scientists have observed a decline in the number of nests. Some causes of this decline include a lack of suitable nesting sites, beach erosion, and human disturbances.

When people approach their nests, the birds become aggressive and chase away intruders. Other animals, like crows, will take advantage of the unprotected nests and feed on the eggs.

Which of these terms best describes the relationship between the crows and the black skimmers?

Use the relationships in the food web below to answer the following question.

Which of these lists all of the predators shown in the food web?

Use the relationships in the food web below to answer the following question.

The relationship between the mice and the insects is an example of

Use the information below to answer the following question.

A scientist wanted to find out if low numbers of fish found in a nearby lake were related to acid rain. During his three-year study, he analyzed rainwater and lake water samples. By gathering samples of fish, he estimated the number of fish in the lake.

Each year he found that both the rainwater and lake water became more acidic, and the number of fish decreased.

His data suggested that acid rain may be responsible for the decrease in the number of fish found in the lake.

The lake ecosystem includes frogs, freshwater algae, and inorganic sediment. Which of these is an abiotic factor contained within the lake ecosystem?

Use the information below to answer the following item.

An insecticide is a chemical that kills insects. Most insects are killed the first time they are exposed to an insecticide. However, some insects carry a gene that enables them to survive their first exposure to an insecticide. When these surviving insects reproduce, this gene may be inherited by their offspring. The number of insecticide-resistant insects usually increases over time because increasing numbers of offspring with this gene are able to survive and reproduce.

What is the ecological relationship between insects and crops?

Use the information below to answer the following item.

Hummingbirds need large amounts of energy to flap their wings between 60 and 200 times per second. Their wings beat so rapidly that it is difficult to see them move. They often appear suspended in air for extended periods of time without changing their location. Hummingbirds have long bills and grooved tongues to reach into flowers to feed on flower nectar. They also feed on insects.

Which term best describes the ecological relationship between hummingbirds and insects?

Use the information and the figure below to answer Numbers 43 through 45.

Use the information and the figure below to answer the following item.

Many plants that grow in tropical rain forests have specialized roots that anchor them to the branches and trunks of trees. They do not harm the trees. These plants get food and water from various sources, including the air and dead organic matter found on the trees.

One example of these plants found in tropical rain forests is the bromeliad. Its leaves form a cup-like structure that is able to hold water. This water provides a feeding and breeding area for many insects and frogs. Snakes and lizards also come to these plants in search of food and water. A cross-section showing the inside of a bromeliad is shown below.

Snakes and lizards come to the bromeliads to feed on frogs and their eggs. The relationship between the snakes, lizards, and frogs can best be described as

A protozoan lives inside a rat and takes its nourishment from the rat’s body. Because the protozoan damages the rat’s brain, the rat loses its fear of cats. A cat attacks an infected rat; the protozoan enters the cat’s body and completes its life cycle.

Which of these describes the relationship between the protozoan and the rat?